Bright wide-angle lens for compact color video cameras

ABSTRACT

A wide-angle lens system for compact color video cameras composed of nine lenses grouped in eight lens components. A first lens component includes a negative meniscus lens convex toward the object, a second lens component includes a positive meniscus lens concave toward the object, a third lens component includes a negative meniscus lens convex toward the object, a fourth lens component includes a positive cemented lens composed of a positive lens and a negative lens, a fifth lens component includes a positive lens, a sixth lens component includes a negative lens, a seventh lens component includes a positive lens and an eighth lens component includes a positive lens.

BACKGROUND OF THE INVENTION

The present invention relates to a wide-angle lens for compact color video cameras.

Recently, compact color video cameras have widely been used in various fields. Also, wide-angle lenses therefor have increasingly been used. If a prior art lens intended for use with an industrial monochrome camera were attempted to be used instead with a color video camera, since the backfocus of such a wide-angle lens is short, it is normally impossible to mount it on a color video camera due to the presence of filters or the like mounted on the front portion of the television camera tube of the camera. Even if the wide-angle lens can be mounted on a particular camera, since the exit pupil position of the prior art wide-angle lens is near the focal plane, non-uniformity of color is inherently generated. Therefore, there is a great demand for a video camera lens in which the non-uniformity of color is negligible and which is suitable for a television camera tube used in a color camera.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a wide-angle lens for compact color video cameras in which the aperture ratio is bright at 1:1.4, the backfocus is 1.75 times longer than the overall focal length, and various aberrations are compensated for to make the lens compatible with a color television camera tube.

Specifically, the present invention provides a wide-angle lens system for compact color video cameras composed of nine lens components grouped in eight lens components. A first lens component includes a negative meniscus lens convex toward the object, a second lens component includes a positive meniscus lens concave toward the object, a third lens component includes a negative meniscus lens convex toward the object, a fourth lens component includes a positive cemented lens composed of a positive lens and a negative lens, a fifth lens component includes a positive lens, and a sixth lens component includes a negative lens, a seventh lens component includes a positive lens and an eighth lens component includes a positive lens.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described with reference to the drawings in which:

FIG. 1 is a cross-sectional view showing a lens of the present invention according to an Example 1;

FIG. 2 is a graph showing various aberration curves for the lens of FIG. 1;

FIG. 3 is a cross-sectional view showing a lens of the invention according to an Example 2;

FIG. 4 is a graph showing various aberration curves for the lens of FIG. 3;

FIG. 5 is a cross-sectional view showing a lens of the invention according to an Example 3; and

FIG. 6 is a graph showing various aberration curves for the lens of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Specific examples of lenses according to the invention will be described in which: r₁, r₂, . . . r₁₉ is the radius of curvature of each lens surface; d₁, d₂, . . . d₁₈ is the lens thickness or the distance between the respective adjacent lenses; N₁, N₂, . . . N₁₀ is the refractive index of each lens, ν₁, ν₂, . . . ν₁₀ is the Abbe number of each lens, and * is the face plate of the television camera tube. Note that the value of backfocus is calculated without the face plate.

EXAMPLE 1

Aperture ratio 1:1.4 F=100 View angle 70.8°

    ______________________________________                                              r.sub.1                                                                              470.236    d.sub.1                                                                            15.97  N.sub.1 /ν.sub.1                                                                   1.62230/53.2                                r.sub.2                                                                              155.922    d.sub.2                                                                            104.44                                                    r.sub.3                                                                              -649.982   d.sub.3                                                                            49.95  N.sub.2 /ν.sub.2                                                                   1.80518/25.4                                r.sub.4                                                                              -297.714   d.sub.4                                                                            49.15                                                     r.sub.5                                                                              535.971    d.sub.5                                                                            36.86  N.sub.3 /ν.sub.3                                                                   1.61800/63.4                                r.sub.6                                                                              113.778    d.sub.6                                                                            131.96                                                    r.sub.7                                                                              217.689    d.sub.7                                                                            86.01  N.sub.4 /ν.sub.4                                                                   1.70514/41.2                                r.sub.8                                                                              -190.178   d.sub.8                                                                            14.01  N.sub.5 /ν.sub.5                                                                   1.71736/29.5                                r.sub.9                                                                              -565.632   d.sub.9                                                                            15.36                                                     r.sub.10                                                                             841.143    d.sub.10                                                                           44.60  N.sub.6 /ν.sub.6                                                                   1.65830/53.4                                r.sub.11                                                                             -260.312   d.sub.11                                                                           16.46                                                     r.sub.12                                                                             -172.018   d.sub.12                                                                           13.52  N.sub.7 /ν.sub.7                                                                   1.80518/25.4                                r.sub.13                                                                             218.193    d.sub.13                                                                           20.89                                                     r.sub.14                                                                             801.641    d.sub.14                                                                           38.09  N.sub.8 /ν.sub.8                                                                   1.67790/55.3                                r.sub.15                                                                             -200.659   d.sub.15                                                                           1.23                                                      r.sub.16                                                                             276.716    d.sub.16                                                                           37.60  N.sub.9 /ν.sub.9                                                                   1.74400/44.7                                r.sub.17                                                                             -880.978   d.sub.17                                                                           61.44                                                     r.sub.18                                                                             ∞    d.sub.18                                                                           20.89  N.sub.10 /ν.sub.10                                                                 1.49782/66.8                                r.sub.19                                                                             ∞                                                             ______________________________________                                          F.sub.1·2·3 = -158.900                                       Backfocus = 179.002                                                      

EXAMPLE 2

Aperture ratio 1:1.4 F=100 View angle 70.8°

    ______________________________________                                              r.sub.1                                                                              473.112    d.sub.1                                                                            15.96  N.sub.1 /ν.sub.1                                                                   1.62230/53.2                                r.sub.2                                                                              155.514    d.sub.2                                                                            108.65                                                    r.sub.3                                                                              -642.428   d.sub.3                                                                            47.93  N.sub.2 /ν.sub.2                                                                   1.80518/25.4                                r.sub.4                                                                              -299.300   d.sub.4                                                                            49.98                                                     r.sub.5                                                                              536.562    d.sub.5                                                                            35.54  N.sub.3 /ν.sub.3                                                                   1.61800/63.4                                r.sub.6                                                                              113.590    d.sub.6                                                                            132.26                                                    r.sub.7                                                                              219.348    d.sub.7                                                                            61.40  N.sub.4 /ν.sub.4                                                                   1.70514/41.2                                r.sub.8                                                                              -190.279   d.sub.8                                                                            14.00  N.sub.5 /ν.sub.5                                                                   1.71736/29.5                                r.sub.9                                                                              -568.478   d.sub.9                                                                            25.52                                                     r.sub.10                                                                             845.859    d.sub.10                                                                           48.65  N.sub.6 /ν.sub.6                                                                   1.65830/53.4                                r.sub.11                                                                             -260.729   d.sub.11                                                                           16.50                                                     r.sub.12                                                                             -171.576   d.sub.12                                                                           13.51  N.sub.7 /ν.sub.7                                                                   1.80518/25.4                                r.sub.13                                                                             216.668    d.sub.13                                                                           18.85                                                     r.sub.14                                                                             807.545    d.sub.14                                                                           37.74  N.sub.8 /ν.sub.8                                                                   1.67790/55.3                                r.sub.15                                                                             --200.434  d.sub.15                                                                           1.23                                                      r.sub.16                                                                             276.116    d.sub.16                                                                           37.45  N.sub.9 /ν.sub.9                                                                   1.74400/44.7                                 r.sub.17                                                                            -827.598   d.sub.17                                                                           61.40                                                     r.sub.18                                                                             ∞    d.sub.18                                                                           20.88  N.sub.10 /ν.sub.10                                                                 1.49782/66.8                                r.sub.19                                                                             ∞                                                             ______________________________________                                          F.sub.1·2·3 = -155.786                                       Backfocus = 179.381                                                      

EXAMPLE 3

Aperture ratio 1:1.4 F=100 View angle 70.8°

    ______________________________________                                              r.sub.1                                                                              473.541    d.sub.1                                                                            15.96  N.sub.1 /ν.sub.1                                                                   1.62230/53.2                                r.sub.2                                                                              155.895    d.sub.2                                                                            108.13                                                    r.sub.3                                                                              --639.702  d.sub.3                                                                            51.44  N.sub.2 /ν.sub.2                                                                   1.80518/25.4                                r.sub.4                                                                              -301.437   d.sub.4                                                                            52.10                                                     r.sub.5                                                                              543.943    d.sub.5                                                                            35.46  N.sub.3 /ν.sub.3                                                                   1.61800/63.4                                r.sub.6                                                                              114.155    d.sub.6                                                                            131.33                                                    r.sub.7                                                                              217.565    d.sub.7                                                                            77.41  N.sub.4 /ν.sub.4                                                                   1.70514/41.2                                r.sub.8                                                                              -191.629   d.sub.8                                                                            14.00  N.sub.5 /ν.sub.5                                                                   1.71736/29.5                                r.sub.9                                                                              -549.137   d.sub.9                                                                            14.15                                                     r.sub.10                                                                             841.499    d.sub.10                                                                           43.48  N.sub.6 /ν.sub.6                                                                   1.65830/53.4                                r.sub.11                                                                             -259.440   d.sub.11                                                                           10.96                                                     r.sub.12                                                                             -172.252   d.sub.12                                                                           21.32  N.sub.7 /ν.sub.7                                                                   1.80518/25.4                                r.sub.13                                                                             217.516    d.sub.13                                                                           22.13                                                     r.sub.14                                                                             816.840    d.sub.14                                                                           37.61  N.sub.8 /ν.sub.8                                                                   1.67790/55.3                                r.sub.15                                                                             -200.680   d.sub.15                                                                           1.23                                                      r.sub.16                                                                             271.327    d.sub.16                                                                           37.20  N.sub.9 /ν.sub.9                                                                   1.74400/44.7                                 r.sub.17                                                                            -1152.429  d.sub.17                                                                           61.40                                                     r.sub.18                                                                             ∞    d.sub.18                                                                           20.89  N.sub.10 /ν.sub.10                                                                 1.49782/66.8                                r.sub.19                                                                             ∞                                                             ______________________________________                                          F.sub.1·2·3 = -155.188                                       Backfocus = 181.980                                                       

What is claimed is:
 1. A wide-angle lens system comprising nine lenses grouped in eight lens components, a first lens component including a negative meniscus lens convex toward the object, a second lens component including a positive meniscus lens concave toward the object, a third lens component including a negative mensicus lens convex toward the object, a fourth lens component including a positive cemented lens composed of a positive lens and a negative lens, a fifth lens component including a positive lens, a sixth lens component including a negative lens, a seventh lens component including a positive lens, and an eighth lens component including a positive lens wherein:Aperture ratio 1:1.4 F=100 View angle 70.8°

    ______________________________________                                               r.sub.1                                                                             470.236    d.sub.1                                                                            15.97 N.sub.1 /ν.sub.1                                                                   1.62230/53.2                                 r.sub.2                                                                              155.922    d.sub.2                                                                            104.44                                                    r.sub.3                                                                              -649.982   d.sub.3                                                                            49.95 N.sub.2 /ν.sub.2                                                                   1.80518/25.4                                 r.sub.4                                                                              -297.714   d.sub.4                                                                            49.15                                                     r.sub.5                                                                              535.971    d.sub.5                                                                            36.86 N.sub.3 /ν.sub.3                                                                   1.61800/63.4                                 r.sub.6                                                                              113.778    d.sub.6                                                                            131.96                                                    r.sub.7                                                                              217.689    d.sub.7                                                                            86.01 N.sub.4 /ν.sub.4                                                                   1.70514/41.2                                 r.sub.8                                                                              -190.178   d.sub.8                                                                            14.01 N.sub.5 /ν.sub.5                                                                   1.71736/29.5                                 r.sub.9                                                                              -565.632   d.sub.9                                                                            15.36                                                     r.sub.10                                                                             841.143    d.sub.10                                                                           44.60 N.sub.6 /ν.sub.6                                                                   1.65830/53.4                                 r.sub.11                                                                             -260.312   d.sub.11                                                                           16.46                                                     r.sub.12                                                                             -172.018   d.sub.12                                                                           13.52 N.sub.7 /ν.sub.7                                                                   1.80518/25.4                                 r.sub.13                                                                             218.193    d.sub.13                                                                           20.89                                                     r.sub.14                                                                             801.641    d.sub.14                                                                           38.09 N.sub.8 /ν.sub.8                                                                   1.67790/55.3                                 r.sub.15                                                                             -200.659   d.sub.15                                                                            1.23                                                     r.sub.16                                                                             276.716    d.sub.16                                                                           37.60 N.sub.9 /ν.sub.9                                                                   1.74400/44.7                                 r.sub. 17                                                                            -880.978   d.sub.17                                                                           61.44                                                     r.sub.18                                                                             ∞    d.sub.18                                                                           20.89 N.sub.10 /ν.sub.10                                                                 1.49782/66.8                                 r.sub.19                                                                             ∞                                                             ______________________________________                                          F.sub.1.2.3 = -158.900                                                         Backfocus = 179.002 where:                                               

r₁, r₂, . . . r₁₉ is the radius of curvature of each lens surface; d₁, d₂, . . . d₁₈ is the lens thickness or the distance between the respective adjacent lenses; N₁, N₂, . . . N₁₀ is the refractive index of each lens; ν₁, ν₂, . . . ν₁₀ is the Abbe number of each lens; and * is the face plate of the television camera tube.
 2. A wide-angle lens system comprising nine lenses grouped in eight lens components, a first lens component including a negative meniscus lens convex toward the object, a second lens component including a positive meniscus lens concave toward the object, a third lens component including a negative meniscus lens convex toward the object, a fourth lens component including a positive cemented lens composed of a positive lens and a negative lens, a fifth lens component including a positive lens, a sixth lens component including a negative lens, a seventh lens component including a positive lens, and an eighth lens component including a positive lens wherein:Aperture ratio 1:1.4 F=100 View angle 70.8°

    ______________________________________                                              r.sub.1                                                                              473.112    d.sub.1                                                                            15.96  N.sub.1 /ν.sub.1                                                                   1.62230/53.2                                r.sub.2                                                                              155.514    d.sub.2                                                                            108.65                                                    r.sub.3                                                                              -642.428   d.sub.3                                                                            47.93  N.sub.2 /ν.sub.2                                                                   1.80518/25.4                                r.sub.4                                                                              -299.300   d.sub.4                                                                            49.98                                                     r.sub.5                                                                              536.562    d.sub.5                                                                            35.54  N.sub.3 /ν.sub.3                                                                   1.61800/63.4                                r.sub.6                                                                              113.590    d.sub.6                                                                            132.26                                                    r.sub.7                                                                              219.348    d.sub.7                                                                            61.40  N.sub.4 /ν.sub.4                                                                   1.70514/41.2                                r.sub.8                                                                              -190.279   d.sub.8                                                                            14.00  N.sub.5 /ν.sub.5                                                                   1.71736/29.5                                r.sub.9                                                                              -568.478   d.sub.9                                                                            25.52                                                     r.sub.10                                                                             845.859    d.sub.10                                                                           48.65  N.sub.6 /ν.sub.6                                                                   1.65830/53.4                                r.sub.11                                                                             -260.729   d.sub.11                                                                           16.50                                                     r.sub.12                                                                             -171.576   d.sub.12                                                                           13.51  N.sub.7 /ν.sub.7                                                                   1.80518/25.4                                r.sub.13                                                                             216.668    d.sub.13                                                                           18.85                                                     r.sub.14                                                                             807.545    d.sub.14                                                                           37.74  N.sub.8 /ν.sub.8                                                                   1.67790/55.3                                r.sub.15                                                                             -200.434   d.sub.15                                                                           1.23                                                      r.sub.16                                                                             276.116    d.sub.16                                                                           37.45  N.sub.9 /ν.sub.9                                                                   1.74400/44.7                                 r.sub.17                                                                            -827.598   d.sub.17                                                                           61.40                                                     r.sub.18                                                                             ∞    d.sub.18                                                                           20.88  N.sub.10 /ν.sub.10                                                                 1.49782/66.8                                r.sub.19                                                                             ∞                                                             ______________________________________                                          F.sub.1·2·3 = -155.786                                       Backfocus = 179.381 where:                                               

r₁, r₂, . . . r₁₉ is the radius of curvature of each lens surface; d₁, d₂, . . . d₁₈ is the lens thickness or the distance between the respective adjacent lenses; N₁, N₂, . . . N₁₀ is the refractive index of each lens; ν₁, ν₂, . . . ν₁₀ is the Abbe number of each lens; and * is the face plate of the television camera tube.
 3. A wide-angle lens system comprising nine lenses grouped in eight lens components, a first lens component including a negative meniscus lens convex toward the object, a second lens component including a positive meniscus lens concave toward the object, a third lens component including a negative meniscus lens convex toward the object, a fourth lens component including a positive cemented lens composed of a positive lens and a negative lens, a fifth lens component including a positive lens, a sixth lens component including a negative lens, a seventh lens component including a positive lens, and an eighth lens component including a positive lens wherein:Aperture ratio 1:1.4 F=100 View angle 70.8°

    ______________________________________                                              r.sub.1                                                                              473.541    d.sub.1                                                                            15.96  N.sub.1 /ν.sub.1                                                                   1.62230/53.2                                r.sub.2                                                                              155.895    d.sub.2                                                                            108.13                                                    r.sub.3                                                                              -639.702   d.sub.3                                                                            51.44  N.sub.2 /ν.sub.2                                                                   1.80518/25.4                                r.sub.4                                                                              -301.437   d.sub.4                                                                            52.10                                                     r.sub.5                                                                              543.943    d.sub.5                                                                            35.46  N.sub.3 /ν.sub.3                                                                   1.61800/63.4                                r.sub.6                                                                              114.155    d.sub.6                                                                            131.33                                                    r.sub.7                                                                              217.565    d.sub.7                                                                            77.41  N.sub.4 /ν.sub.4                                                                   1.70514/41.2                                r.sub.8                                                                              -191.629   d.sub.8                                                                            14.00  N.sub.5 /ν.sub.5                                                                   1.71736/29.5                                r.sub.9                                                                              -549.137   d.sub.9                                                                            14.15                                                     r.sub.10                                                                             841.499    d.sub.10                                                                           43.48  N.sub.6 /ν.sub.6                                                                   1.65830/53.4                                r.sub.11                                                                             -259.440   d.sub.11                                                                           10.96                                                     r.sub.12                                                                             -172.252   d.sub.12                                                                           21.32  N.sub.7 /ν.sub.7                                                                   1.80518/25.4                                r.sub.13                                                                             217.516    d.sub.13                                                                           22.13                                                     r.sub.14                                                                             816.840    d.sub.14                                                                           37.61  N.sub.8 /ν.sub.8                                                                   1.67790/55.3                                r.sub.15                                                                             -200.680   d.sub.15                                                                           1.23                                                      r.sub.16                                                                             271.327    d.sub.16                                                                           37.20  N.sub.9 /ν.sub.9                                                                   1.74400/44.7                                 r.sub.17                                                                            -1152.429  d.sub.17                                                                           61.40                                                     r.sub.18                                                                             ∞    d.sub.18                                                                           20.89  N.sub.10 /ν.sub.10                                                                 1.49782/66.8                                r.sub.19                                                                             ∞                                                             ______________________________________                                          f.sub.1·2·3 = -155.188                                       Backfocus = 181.980 where:                                               

r₁, r₂, . . . r₁₉ is the radius of curvature of each lens surface; d₁, d₂, . . . d₁₈ is the lens thickness or the distance between the respective adjacent lenses; N₁, N₂, . . . N₁₀ is the refractive index of each lens; ν₁, ν₂, . . . ν₁₀ is the Abbe number of each lens; and * is the face plate of the television camera tube. 